Sample Essay on Custom in International Law

Custom in International Law


This paper discusses custom in international law. Custom in the international laws are developed from local customary laws. The United Nations, its member states, international jurists as well as the International Court of Justice directly express customs as the primary sources of international law. This is consistent with the existing principles of treaties and law. As at now, so many world’s governments are now using the principles of customary international laws. This essay investigates and discusses some of these issues.

Custom in International Law

Ideally, a customary international law should contain various proponents like principles, rules, and norms that can apply to any state. The principles as well as the norms should not be limited to only a particular state of an exclusive group. For instance, rules that relates to the airspace, outer space, warfare, immunities, and samongst others, should apply equally to all states that are concerned with these issues. Similar principles, norms, and rules should be used to all the participating countries. The results of several cases suggest the exclusive application of general customs in global laws. For instance, there are cases concerning the overall principles of international laws, the collision of ship from different countries on the high seas, as well as the construction of treaties, all suggesting the exclusive application of customs in international law.

Conversely, there are special customs international laws. These traditional customs specifically deal with non-generalized topics. For example, the rights to a particular section of the world. For instance, cases involving acquisitive prescription, boundary disputes,as well as global servitudes may form part of the special custom international law. Most of these cases deal with rules and principles that are expressly limited to some countries or regions. However, such customs are unable to expressly determinate different classes of people. A good example is the Latin American’s asylum laws. In essence, it is a thin line that separates general custom from the special custom in international law.

According to Malcolm (2008), customs are not particular to any department or area of public international law. Instead, it is international law. Customs in law is defined as the established pattern of behavior that is both objectively and verified within a particular social setting. This issue surfaces wherever there are arguments of the International Court of Justice and other international organizations that claim the imprimatur of international custom while others not only question the principles but their alleged status as customary. There are several issues affecting the custom in international law.

Recognizing Custom in International Law

There are two general conditions that determines the existence of customs in international laws. They include (1) the special legal practicesthat are maintained by some countries, and (2) the special legal practice that other relevant actors consider as law. The latter is expressly known as opinio juris. Several customary laws are established to manage the long established standards of the community in a given locale. In the global perspective, the term is applied to specific elements of legal standards of practice, as expressed in the international law, have been universally accepted as the correct basis for action. For example, laws against slavery and piracy are universally accepted as the correct basis for action. In many cases, customary laws are supported by previous supportive court rulings and relevant cases. This is done to give it more weight and demonstrate the trajectory of the evolution as well as the interpretation of the law.

According to the definition given by International Court of Justice Statute in Article 38(1) (b), customary international law is evidence of general practices that are accepted as laws. This is determined by two important factors. These factors include the general practice of the country and the countries that have accepted the practice as law. Different states now accept and recognize different types of custom in international law. There is no absolute uniformity in the recognition and acceptance of customs in international law. It is essential to note that some customs in international law rise to become jus cogens while a small group of countries simply follows others. In the former scenario, the customs may develop into jus cogens level. This is basically due to open acceptance as non-derogable rights by the international community.

Jus cogens is a principle in the customary laws. It is followed in the acceptance of custom sin international law. The international society accepts this principle as the basic legal norms through which people cannot permit any form of derogation. The jus cogens norms particularly is derived from the principles of natural laws. Any law that contradicts or conflicts the norms and principles of jus cogens is, therefore, considered null and void in the international perspective. For example, any country that allows slavery, genocide, torture, the aggression war or any form of crime that is against the principle of humanity is considered violating the custom in international law. States are bound to adopt and follow customary international law regardless of whether or not they have codified.

The Elements of Custom

It has  been said  that the  standard of  conduct which  follows from  a  settled practice  becomes custom when  it is  accepted as  a  rule of  legal nature. Article  38,  paragraph  1(b),  of  the  Court’s  Statute,  requires  that  the  practice  be  “accepted  as  law”,  and  the  problem  of  acceptance  brings  to  the  fore  the  problem  consent  in  the  making  of  custom,  and  particularly  in  the  emergence  of  the  opinion  juris. This can be defined as the ‘subjective’ mental element, which makes ‘objective’ usage a norm of international law.

To establish whether custom exists on a certain legal matter, certain conditions must be fulfilled. For example, the primary concern of the acts should to attain the settled practice. Besides, they must be performed in a manner that provides evidence of the practice is rendering obligatory. The attitude might take several diferent forms according to the merits of the specific situation. They may simply tolerate the practice without consenting to it expressly or tacitly.

The attitude of mere toleration is sufficient when the claims put forward by the participants do not impose any duties on the non-participants. Thus, consent is necessary to the formative period of a customary rule. Many dualist theorists argue that usus (regulations of behavior) consists of all relevant constituents on the spectrum from a pure deed to pure word. On the contrary, opinio juris (legally required) becomes a mental or subjective element. In this case, it is typically assumed based on the usus.

Several elements might constitute the custom laws especially in the localized restriction. However, the elements might vary when it comes to the international law. When it comes to custom laws, the theorists of international laws are overlyinterestedin understanding what makes up the custom law. They also want to know if and how the discursive normative practice account fit into the concept of custom law in the international perspective. It is also essential to note that the qualities of a norm as a significantly normative custom is its integration into a discursive, deed-based system of norms.

Thus,  what  qualifies  a  given  custom  as  legally  significant  in  some  legal  system  is  whether  that  custom  is  incorporated  into  the  larger  set  of  norms  of  that  legal  system,  or  whether  it  is  integrated  into  a  custom regime  that  in  turn  is  incorporated  into  the  legal  system. Normative practice is, therefore, those who follow customs in the mode of their participation in the practice.

The Normativity of Custom

Over the last half a century,  many rules  of customary  international  law  have been thought to bind universally irrespective of whether  the party subject to them  has signed. To make the customary laws are universally binding. They certainly impose an obligation omnium. Despite this push for the use of customary laws universally, some leeway has been directly given to the “persistent objectors.” This has subsequently reduced the impacts as well as applicability of customs as applied in the international laws. But, of course, the  problem of  scope  gets  worse  once  the principles of  humanitarian,  human rights,  and  environmental  law are considered.

New problems arise when the principles of human rights, humanitarian, as well as the environmental laws are considered the basic pillars of customary international laws. This is because these principles, although good, just hold the intersection between discrete parties or states. Instead, they form part of the erga omnes. By this virtue, they simply bind and entail all rights that are held by various states. They undertake all types of duties and functions such as the state’s role in the protection of the right-holders. This happens regardless of the specific relations that exist between the state and the right-holders. In the words of the International   Court of   Justice case, these explicitly express the obligations of a State towards the requirements of the international community as a whole.

Customs are practiced in  communities in which they have been prescribed to. They   are   the practiced norms of that particular   community. These are more than  mere  rules that are followed by individuals out of fear. In addition they are not mere rules followed as a  matter of personal policy. These rules,  as much as they apply to that particular  community,  do not  necessary apply  to the  rest  of  the  other  social  organizations. Several communities widely follow the norms  of  independent  conviction  because this  convergence of behavior  of members  allows them  believe that it is their moral  responsibility  to abide  by the same. For  instance,  customs dictate  that  it  is  important  to  be  neighborly  and  to deal  honestly  with  others. This happens regardless  of  whether  communities are doing eth same thing. They may  be wrong  about  it,  but then,  this  only  serves  to  prove that  morality is  closely entwined  with customs,  more  than  it  is  acknowledged.

The   Statute of the   International   Court of   Justice described a customary international law as a general practice of law. In  a  2003  decision  of  the  United  States  Court  of  Appeals  (Flores  vs. Southern   Peru  Copper  Corporation),  described  customary  international  law. According to this decision, no  distinction  is evident  between  this  concept  and  the  widely-held  definition  of  international  law. This is also referred to as the  law  of  nations. According to this definition, customary  international  law  is  those  rules,  standards  or  customs  (a)  affecting  the  relationship  between  states  or  between  an  individual  and  a  foreign  state  and  (b)  used  by  those  states  for  their  common  good  and/or  in  dealings  inter  se.

The customary internationallawsare meant to deal only with the wrongs that are of mutual concern. On the contrary, it does not address wrongs that are merely of several concerns. Those who participate in a custom’s practice undertake several different commitments. They include commitments (a)  to judge  certain  performances  as  appropriate  or  inappropriate;  (b)  to  act  when  the  occasion  arises  in  accord  with  these  judgments;  (c)  to  challenge  conduct  that  falls  short  of  these  judgments;  and  (d)  to  recognize  appeals  to  the  judgments  as  vindications  of  their  actions  or  valid  criticisms  of  them. As a rule, the customary international law is design and created through the uniform and constant practice of states. This also includes other communities or states that are subjects of the international law. Applied this way, customs directly expresses the legitimate expectation in the future of similar situation.

International Law

In the international law perspective, the customary laws might imply the Law of Nations. Alternatively, it might refer to the legal norms that have developed in the country through the exchange of custom over a long period of time. These customary exchanges might extend between states. The developed of customary laws may be based on either aggression or diplomacy. In essence, legal obligations may arise especially between states as a way of carrying out their affairs in accordance with their past acceptable practices. There are chances that these customs can alter over a given period of time. States that use particular acts might base the change on either the acceptance or the rejection. These might cause come differences in the application of customs in the international law.

Some of the principle, rules, and norms of customary laws have successfully achieved the force of peremptory norms in the international perspective. It is not right to alter or violate the peremptory norms. However, alteration and violation of the peremptory norms is only accepted through the application of a norm of comparable strength. This is done to help strengthens the force of costmary international laws. However, not all principles, norms, and rules of customary laws have achieved the status of peremptory norms. The significance of peremptory norms is that they gain significant strength especially from their universal acceptance. Good examples of peremptory norms are prohibitions against slavery and genocide. The international customary laws are not similar to international treaties. Unlike customary internal laws, treaties consist of explicit agreements between states that allow them to assume obligations. However, many treaties attempt to codify the existing customary laws in the international context.

Customary Law in Contemporary Legal Systems

The majority of the modern legal systems recognize the customary law. In particular, it is recognized as a significant sources of law within many contemporary jurisdictions especially those relating to the civil law traditions. In this case, customary laws may be subordinate to both the required regulations and statutes of the state. However, the importance of custom as the primary source of law in civil tradition is slight and decreasing. Nonetheless, in many countries, many types of customary laws exist alongside the nation’s official laws. This condition is referred to as legal pluralism. Some of the countries using legal pluralism include Denmark, Uganda, Norway, and Sweden among others.

The principle of customary laws is widely adopted in the contemporary principles of property laws. The principle of property laws recognizes and gives legal right to continue something that has been practice for long instead of objecting it. This applies in areas such as occupying or using the land to which a person has no title. It is practiced in contemporary laws that something, which has been practiced from the beginning by a particular community or locality, may rise to the legal status in the form of local law. There are precise legal criteria that define the custom. The legal precedent defines ‘time immemorial’ as a period of 12 years.

Customary ancient laws form the constitution foundations in countries such as Canada. This has made customary laws to have broadening influence within and outside Canada. In addition, customary laws continue to exist in Scandinavian countries where they have a significant influence on the constitutional foundation of the country. Not forgetting, customary laws are widely used in most third world countries especially in Africa and Asia continents. In particular, customary laws are used alongside civil. They might also be used alongside common laws in third world countries. A good example is Ethiopia where there are more than 60 systems of customary laws used alongside the countries legal codes. Some of these customary laws operate independent of the established formal legal system employed by the state.

Custom in the Global Environment

Custom in the international law has functions in the social environment. The primary agents involved are nation-states. Several international law theorists argue that nation-states being the primary agents limits to a great extent the force, nature, as well as the scope of the customs within its domain. In addition, this limits largely the types of norms that can arise within this domain. However, controversial instance of custom in international law usually arise due to constant interaction, tolerances, and claims as to the ability of the sovereign state. In such case, the custom may generate rights and obligations that are bilateral. These are correlative duties and rights. Furthermore, such customs may run only between individual sovereign states. This strictly reduce the level of bilateral interaction. This typical strict bilateral interaction between states is essential to and intrinsic to the type of state practices that eventually leads to the formation for customary international laws.

The process of custom in international laws is triggered only situations in which countries interacts with each other. Without this interaction, custom might not be applied in the international law. The interaction also ensures the custom laws continue to work in the international perspective. This argument, even though it sees sound, possesses serious challenges to human rights as well as other humanitarian principles. This argument also seems to challenge the principles of normative practice. The international dynamics of the global order differs significantly in kind from one country to another. Also, some people are skeptical about the custom in international law because it has direct impact on the human rights and humanitarian principles. In particular, they are skeptical about the use of customs to defend the principles of human rights and humanitarian. Customs does not provide a more secure and universal doctrine of defending the human rights and humanitarian principles.


Shaw, M. (2008). International Law (Sixth edition), New York, Cambridge University Press, pp. 72-93.